1. Field of the Invention
The present invention relates to an image recording apparatus based on the exposure of a photosensitive recording medium to the light, and particularly to the adjustment of the level of exposure.
2. Description of the Related Art
An image recording apparatus of this type incorporates a light exposing device which irradiates the light from a light source to the original text and exposes the photosensitive medium to the light which has been subjected to the influence of the original text Conventionally, an incandescent lamp, such as a halogen lamp as disclosed in U.S. Pat. No. 4,806,984, or a fluorescent lamp is used for the light source and the light output of the light source is varied for the adjustment of the level of exposure thereby to adjust the contrast of the recorded image or the like.
However, in case an incandescent lamp is used for the light source, a change in the light output creates a variation in the hue of light, resulting in deviation from the range of wavelength sensitivity of the photosensitive medium. The photosensitive medium has its sensitive wavelength range determined from the composition of the medium, and the deviation from the wavelength range can cause such impropriety as the collapse of color balance. Although a fluorescent light source retains the wavelength even if the light output is changed, the adjustment of its light output necessitates a complex circuitry, resulting in an expensive apparatus.